Ionization and dissociation equilibrium in strongly magnetized helium atmosphere
Bibliographic record
Abstract
Recent observations and theoretical investigations of neutron stars indicate that their atmospheres consist not of hydrogen or iron but possibly other elements such as helium. We calculate the ionization and dissociation equilibrium of helium in the conditions found in the atmospheres of magnetized neutron stars. For the first time, this investigation includes the internal degrees of freedom of the helium molecule. We found that at the temperatures and densities of neutron star atmospheres, the rotovibrational excitations of helium molecules are populated. Including these excitations increases the expected abundance of molecules by up to two orders of magnitude relative to calculations that ignore the internal states of the molecule; therefore, if the atmospheres of neutron stars indeed consist of helium, helium molecules and possibly polymers will make the bulk of the atmosphere and leave signatures on the observed spectra from neutron stars. We applied our calculation to nearby radio-quiet neutron stars (RQNS) with Bdipole∼ 1013–1014 G. If helium comprises their atmospheres, our study indicates that isolated neutron stars with TBB∼ 106 K such as RX J0720.4−3125 and RX J1605.3+3249 will have He+ ions predominantly, while isolated neutron stars with lower temperature (TBB∼ 5 × 105 K) such as RX J1856.5−3754 and RX J0420.0−5022 will have some fraction of helium molecules. We found that ionization, dissociation and electric excitation energies of helium molecules are larger than 100 eV at B≳ 1013 G. On the other hand, rotovibrational excitation energies are in the range of 10–100 eV at B= 1012–1014 G. If helium molecules are abundant, their spectroscopic signatures may be detected in the optical, ultraviolet and X-ray band.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".